This invention relates generally to a method of manufacturing a thermal ink jet (TIJ) print cartridge and a TIJ print cartridge manufactured using the method. More particularly, this invention relates to a method of filling an ink reservoir of a TIJ print cartridge with ink in a manner so as to reduce the amount of air trapped in a standpipe chamber of the TIJ print cartridge.
Thermal ink jet (TIJ) technology is widely used in today""s printers. Very generally, a TIJ print cartridge includes a TIJ printhead that has an orifice plate attached to a printhead die. Orifices or nozzles in the orifice plate are aligned with transducers on the printhead die. The transducers are selectively actuatable to eject droplets of ink through the corresponding nozzles onto a print medium. U.S. Pat. No. 5,874,978 discloses one such TIJ print cartridge. The cartridge further includes an ink reservoir for storing ink. A standpipe that defines a standpipe chamber connects and allows ink from the ink reservoir to flow to the printhead. A screen filter is disposed at the entrance of the standpipe chamber to prevent particulate contaminants in the ink from reaching and clogging the printhead.
During manufacturing, the print cartridge is primed by vacuuming air out of the standpipe chamber to remove air trapped therein. However, priming is unable to remove the trapped air entirely. Furthermore, over time a diffusion phenomenon results in air from outside the standpipe chamber penetrating the screen filter to increase the overall amount of air trapped in the standpipe chamber. Air is further introduced in the standpipe chamber during operation of the print cartridge. During operation, cool ink is drawn into the standpipe chamber and is warmed as the ink flows toward the printhead. The printhead generates heat as its resistors are activated or fired to eject droplets of ink from the nozzles. For a primarily water-based ink, the solubility of air decreases as the ink is heated. As a result, air is driven out of the ink, and diffuses into any preexisting air bubbles in the standpipe chamber. Over time, the standpipe chamber may be filled with sufficient air to restrict the proper flow of ink into the standpipe chamber. Printing under such conditions of the print cartridge results in print defects. This increase in air in the standpipe chamber occurs both in vented foam-filled print cartridges as well as print cartridges using a spring-bag type of backpressure mechanism.
As the amount of air increases in the standpipe, there will come a time when the trapped air causes complete ink starvation or depriming of the printhead to render the print cartridge useless. The amount of air left in a print cartridge when it leaves the production line has an effect on the overall useful life of the print cartridge.
There is also a disadvantage associated with priming of a print cartridge. Priming causes both air and ink to be vacuumed out of the print cartridge. The ink that is vacuumed out of the print cartridge is not reused because of it typically contains more contaminants.
According to an aspect of the present invention, there is provided a method of manufacturing an ink jet print cartridge. The method includes fabricating a cartridge. The cartridge includes a body that supports a printhead. The printhead includes an orifice plate having orifices formed therethrough. The cartridge includes an ink reservoir with a backpressure mechanism and at least one standpipe defining a stand pipe chamber for delivering ink from the reservoir to the printhead. A filter is disposed adjacent the chamber for preventing contaminants in the ink from reaching the printhead. The method further includes introducing ink into the reservoir, covering the orifices of the orifice plate to prevent leakage of ink through the orifices, and subjecting the cartridge to a predetermined centrifugal force to force ink into the standpipe chamber to displace air trapped therein.
According to another aspect of the present invention, there is an ink jet print cartridge manufactured according to the above-mentioned method.
According to yet another aspect of the present invention, there is provided a method of manufacturing another ink jet print cartridge. The method includes fabricating the cartridge. The cartridge includes a body that supports a printhead. The printhead includes an orifice plate having orifices formed therethrough. The cartridge further includes an ink reservoir with a back pressure device disposed therein and a standpipe defining a standpipe chamber for delivering ink from the reservoir to the printhead. A filter is disposed adjacent the standpipe chamber for preventing contaminants in the ink from reaching the printhead. The method further includes introducing ink into the reservoir and subjecting the cartridge to a predetermined centrifugal force to force ink away from the standpipe chamber to displace air in the reservoir to force the air to collect adjacent the standpipe. The method also includes priming the cartridge by drawing the air out of the cartridge through the orifices.